In spectral cone beam computed tomography systems a radiation device for providing a cone beam, which is formed by x-rays, and a detector comprising a three-dimensional arrangement of detection elements for generating detection values are rotated around a rotational axis aligned with a subject, wherein a computed tomography image of the subject is reconstructed based on the generated detection values.
The detector comprises several two-dimensional orthogonal arrangements of detection elements, wherein each two-dimensional orthogonal arrangement of detection elements forms a respective plane of detection elements and wherein the planes of detection elements are parallel to the rotational axis and are aligned with the x-rays in the fan direction of the x-rays.
Detection values, which have been generated at different depths within the detector, correspond to different energies such that the detection values are spectral detection values. The quality of the spectral detection values can be reduced due to cross talk in the cone direction, which can lead to artifacts in the computed tomography image and hence to a reduced image quality.